Regulation of Cyclin T1 and HIV-1 Replication by MicroRNAs in Resting CD4 ⁺ T Lymphocytes

Abstract

The replication of integrated human immunodeficiency virus type 1 (HIV-1) is dependent on the cellular cofactor cyclin T1, which binds the viral Tat protein and activates the RNA polymerase II transcription of the integrated provirus. The activation of resting CD4؉ T cells upregulates cyclin T1 protein levels independently of an increase in cyclin T1 mRNA levels, suggesting a translational repression of cyclin T1 in resting CD4 ؉ T cells. Hypothesizing that microRNAs (miRNAs) repress cyclin T1 translation in resting CD4؉ T cells and that this inhibition is lifted upon cell activation, we used microarray expression analysis to identify miRNAs miR-27b, miR-29b, miR-150, and miR-223 as being significantly downregulated upon CD4 ؉ T cell activation. The overexpression of these miRNAs decreased endogenous cyclin T1 protein levels, while treatment with the corresponding antagomiRs increased cyclin T1 protein levels. An miR-27b binding site within the cyclin T1 3= untranslated region (3=UTR) was identified and confirmed to be functional after the mutation of key resides abrogated the ability of miR-27b to decrease the expression of a luciferase reporter upstream of the cyclin T1 3=UTR. Ago2 immunoprecipitation revealed an association with cyclin T1 mRNA that was decreased following treatment with miR-27b and miR-29b antagomiRs. Cells overexpressing miR-27b showed decreased viral gene expression levels of the HIV-1 reporter virus and a decreased replication of strain NL4.3; a partial rescue of viral transcription could be seen following the transfection of cyclin T1. These results implicate miR-27b as a novel regulator of cyclin T1 protein levels and HIV-1 replication, while miR-29b, miR-223, and miR-150 may regulate cyclin T1 indirectly.

MicroRNA and HIV

“…Similar effect has been observed by miR-27b, miR-29b, miR-150, miR-223 [4,10,20,21]. In fact, it has been shown that when miR-27b, miR-29b, miR-150, and miR-223 were overexpressed, endogenous cyclin T1 protein levels decreased; on contrary, if cells were treated with their antagonmiRs, cyclin T1 protein levels increased [23]. In the same way, it has been described that miR-198 and miR-27b are highly expressed in monocytes and resting CD4 + T cells as well as miR-198 is also over-expressed in macrophages [2,6,10].…”

“…In the same way, it has been described that miR-198 and miR-27b are highly expressed in monocytes and resting CD4 + T cells as well as miR-198 is also over-expressed in macrophages [2,6,10]. Likewise, CD4 + T cells activation seems to be associated with a down-regulation of this miRNAs and an up-regultion of Cyclin T1 [23]. SIRT1 can be targeted by miR-34a and miR-217, causing Tat function inhibition [20,21].…”

Bromodomain and Extra-terminal (BET) Bromodomain Inhibition Activate Transcription via Transient Release of Positive Transcription Elongation Factor b (P-TEFb) from 7SK Small Nuclear Ribonucleoprotein

“…Our results indicate that JQ1 activates HIV transcription from J⌬K cells as well as other latently infected transformed cell lines (data not shown). Although JQ1 alone did not reactivate HIV from latently infected primary resting T cells because their levels of P-TEFb are vanishingly low (6,35), JQ1 could become a candidate for combinatorial anti-latency therapy with SAHA and/or other T cell-activating compounds. To this end, during the preparation of this manuscript, Montano and colleagues (36) reported that JQ1 could reactivate minimally latent HIV in , and cell lysates were subjected to immunoprecipitations (IP) with anti-CycT1 (left panels) and anti-BRD4 (right panels) antibodies.…”

The role of microRNAs in HIV infection

“…It was discovered that miR-198 targets the cyclin T1 mRNA, which encodes a HIV-1 Tat cofactor, to confer differences in permissiveness between monocytes and macrophages to HIV infection [49]. In other study, Chiang and colleagues also found that, in different cellular contexts, other miRNAs regulate cyclin T1, such as miR-27b, miR-29b, miR-223, miR-150, that can explain the expression differences of HIV in resting versus activated T cells [50]. Triboulet and colleagues found that HIV-1 infection was also associated with either up-or downregulation of specific miRNA clusters [51].…”